I already talked about my ideas on another thread about ways to divide zoos into sections but I feel they're relevant here. The first is Living Fossils. This one's pretty self-explanatory. With this section, I don't really have too many specific species in mind, more general groups, so its pretty flexible in that regard. The types of animals I'd like to see here are sengis, elephant shrews, pelicans, mousebirds (maybe in a walkthrough aviary), seriemas, giant salamanders, arowanas, sturgeon, lamprey, mudskippers, and horseshoe crab. As for specific species, I'd include tuatara, xenopeltis (the exhibit should be done in a way that highlights their iridescence, emphasizing the beauty that can exist in widely disliked animals like snakes), and chambered nautilis. I think the headliner should be a crocodilian. Any species would work, but I really like the idea of using Cuban crocodiles. The reason is that they are the best at running of the extant crocodilians. Some prehistoric crocodilians were land-based predators with long legs and impressive running abilities. This could pay homage to that. It could also be an opportunity to teach people about this through signage. I really like the idea of this exhibit being really grandiose and giving visitors the opportunity to see them at multiple angles. Its ambitious, but an underwater viewing tunnel would be really cool.
I'm also really attached to the idea of including coelacanths, although based on my research, they are not viable in captivity, so this is not within the realm of possibility, at least not now.
As for the theming, I really like the idea of it being made to look like a fossil dig site, with the fossils of iconic extinct species in the rock walls and the ground. I also like the idea of incorporating living fossil plants into the landscaping. The signage would also incorporate facts about these animals and why they managed to endure so much change.
My second idea is an area featuring animals once not believed to be real. This would include okapi, any pelican species, komodo dragon, any kangaroo species, and any rhinoceros species. As the headliner, ideally it would be a platypus, the poster child of sorts for animals once not believed to be real. However, I realize they are extremely hard to care for it captivity, so this may not be possible. In which case, okapi would make a great second choice as the headliner. Although they are not animals, I'd love if it could have a carnivorous plant exhibit as well. I really like the idea of making it look like a fantasy realm, maybe taking some inspiration from fantasy media. Another way to drive home the theme would be to incorporate large, life-like statues of well-known mythical creatures. They could be posed to interact with the environment and the visitors (for example, a griffin perching on a tall rock, looking down on the path where visitors walk). As for the signage, I really like doing it in the style of a bestiary. It would have information about their history of discovery and how it was eventually found to be real, and also incorporate the information you'd normally see in zoo signage so visitors can learn about the animals themselves.